Credit control system

ABSTRACT

A credit control system which positively authorizes every credit purchase, furnishes account balance status and accumulates the dollar amount of every credit purchase. Customer account numbers, status, credit limit and account balance are stored in a magnetic memory. Remote keyboard units interrogate the memory as to account number and amount of purchase for each purchaser. If the status of the account is valid and there is a positive credit balance, a credit authorization signal is received at the remote keyboard unit. If the status of the account is invalid, or if the status of the account is valid and the credit balance is negative, a credit denial signal is received at the remote keyboard unit, and a credit authorizer unit is activated. The credit authorizer unit permits manual electronic inspection of the credit file of interest to determine if credit should be authorized for the current transaction. If credit is to be authorized, or denied, a credit authorization, or denial signal is received at the remote keyboard unit.

United States Patent [191 Michels et a1.

[ 1 March 6, 1973 CREDIT CONTROL SYSTEM [75] inventors: Lawrence S.Micliels, Palos Verdes Peninsula; George F. Minka, Torrance; Donald G.Kovar, Palos Verdes Peninsula; Robert V. Harper, Harbor City, all ofCalif.

Assignee: TRW Data Systems, Inc.,Torrance,

Calif.

[22] Filed: Dec. 28, 1970 [21] Appl. No.: 101,712

[52] U.S. C1. ..340/149 R, 235/61.7 B, 340/152 R [51] Int. Cl. ..G06k5/00, H04q 5/00 [58] Field of Search .....340/149, 149 A, 152;

235/61.7 B, 61.7; 179/2 CA [56] References Cited UNITED STATES PATENTS3,559,175 1/1971 Pomeroy ..340/149 A 3,564,210 2/1971 Presti ..340/149 A3,576,539 4/1971 Huber ..340/l52 3,594,727 7/1971 Braun ..340/1523,484,744 12/1969 Gertler et al. ..l340/146.1

Primary Examiner-Donald J. Yusko Attorney-Daniel T. Anderson, Harry 1.Jacobs and Edwin A. Oser 5 7 ABSTRACT A credit control system whichpositively authorizes every credit purchase, furnishes account balancestatus and accumulates the dollar amount of every credit purchase.Customer account numbers, status, credit limit and account balance arestored in a magnetic memory. Remote keyboard units interrogate thememory as to account number and amount of purchase for each purchaser.If the status of the account is valid and there is a positive creditbalance, a credit authorization signal is received at the remotekeyboard unit. If the status of the account is invalid, or if the statusof the account is valid and the credit balance is negative, a creditdenial signal is received at the remote keyboard unit, and a creditauthorizer unit is activated. The credit authorizer unit permits manualelectronic inspection of the credit file of interest to determine ifcredit should be authorized for the current transaction. If credit is tobe authorized, or denied, a credit authorization, or denial signal isreceived at the remote keyboard unit.

11 Claims, 14 Drawing Figures l TtETflaARB GFolTP r Bur-FER UNIT I 1 1|llOb 1 l 10in H B" I| 1 37" I Mivdfiie m H 1 c I Buffer Communication 1(whom Module Adopter Module 1 I 1| Ion: 10m 2 |U Qe lm l E I IL E 'EUNIT Electronic. I I

l22 I l' I 123 I I Control 8 Printer 1 I Dllploy 1 PATENTEUMAR 6 I975SHEET 01 0F 12 Processor Unit Duto ' Distributor CENTRAL PROCESSORTupe-To-Dlsk Unit ope CONTROLI l Control Data Modem DATA l4 Enquiry D010Modem Buffer Umf DATA ENQUIRY Unit Authorizer IO) Keyboard GrouplNVENTORS Lawrence S.Michels George F Minko Donflld G. Kovur Robert V.Harper fi 2 ATTORNEY PATENTEUHAR 6l975 3119,92? SHEET U3UF 12 POSITIVEBY EXCEPTION FULL POSITIVE NEGATIVE ls Purchase 2 50 7 504 Send StatusSend Status Response Res aonse Send Status Response -r Accum. Amt+Purchosez Put Sta Am PU TChQSC Amount To Accum. Amt

On File Send Green Send Green Status Status Response Response A-SIO F 5lNVEttTORS Lawrence F Mlchels Gear e F Min ka Dona d 6- Kovar Red RobertV. Harper Y= Yellow G= Green y Valid Account Number=Check DigitVerification l O Status Response Sent ATTORNEY PATENTEUEAR 618733,719,927

SHEET our 12 ENTER ACCT. N0 AND PURCHASE AMT ACCT. NO. ON EiLE isPURCHASE SEND STATUS RESPONSE PUT ACCT. N0., A ii r i ACCUM AMT. ON FILEAMgMg PlgRgiii-l A'Mi? I ADD PURCHASE AMT. TO ./5o9 ACCUML AMT, l

5|O SEND GREEN sEi io e r E eri A s PJn s E RESPONSE 5'7 INVENTORS 7Lawrence F Michels George F Minko- Donald G. Kovcir R=Red Robert V.Harper Y=Ye||ow G= Green BY Volid Account Number= Check DigitVerification 0 Status Response ATTORNEY PATENTEUMAR 6 I973 SHEET 050! 12ALlZE GRAM OUTPUT DATA 604 RES DATA REA FLAG SET PROCESSOR AVATLABLEFLAG INVENTORS DISTRIBUTOR INPUT Lawrence S. Michels George F MinkaDonald G- Kovar Robert Harper X AT TORNEY PATENT EDTTAR 6 I975 STOREPROCESSOR ADDRESSIN ZERO COUNTER STORE COMMUN. ADAPTER ADDRESS IN OUTPUTREGISTER LOAD DATA 'STORE CONTROL CHARACTER STORE TRACK SELECT ADDRESSSTORE ADD/SUBTRACT FLAG RELEASE SHEET 06 0F 12 Slow LOAD DATA Gil WAITFOR RELEASE RESET PROCESSOR AVAILABLE I Fig. 6B

INVENTORS Lawrence S. Michels George F Minkc A Donald G. Kovor RoberrHarper ATTORNEY PATENTEUMR s 1575 SHEET [17 [1F 12 WAIT FOR START OFREAD CYCLE S23 RESET RECORD COUNTER SEARCH FOR SEARCH FOR ZERO RECORDS 7ACCOUNT NUMBER T e W LOOK FOR I COMPARE ALL ZERO ACCOUNT RECORD NUMBERSZERO RECORD 34 INCREMENT RECORD COUNTER STORE SI 82 IN OUTPUT /626REGISTER RESET TRACK FULL FLAG SET WRITE I FLAG ADD lNPUT SUBTRACT INPUTAMOUNT TO AMOUNT FROM STORED AMOUN T STORED AMOUNT 646 STORE RECORD 63?N COUNTIN ADDRESS REGISTER Y STORE RESULP A b 629 OUTPUTINEGISTER aINVENTORSI Lawrence S Michele George F MinkO Donald G.KOvOr Robert V HOrer I BY p TORNEY PATENTEIJIIIR ems 3719,92?

SHEET 08 0F 12 STORE TEST STORE INPUT AMOUNT IN AMOUNT IN OUTPUTREGISTER OUTPUT REGISTER sToRE TEST PARITY AMOUNT SWITCH OK IN OUTPUT640 R GISTER 64| 654 RESET TRACK FULL FLAG OVERLIMIT sss STORE YELLOWSTORE GREEN S'GNAL OUTPUT SIGNAL IN OUTPUT REGISTER REGISTER 642 i T I/656 sTORE RECORD TRANSFER OUTPUT TRANSFER OUTPUT COUNT IN TO INPUT ToINPUT ADDRESS REGISTER REGISTER REGISTER 657 sET wRITE SET DATA SET DATAFLAG READY FLAG READY FLAG RESET WRITE FLAG STORE YELLOW OR RED SIGNALIN OUTPUT REGISTER POSITIVE MODE INvENTORs N Lawrence S.Miche|s George FMinkO Donald G. KOvOr Robert V Harper ATTORNEY I FLAGGED RESET S FLAG'PATENTEDHIR' 6m SHEET DSUE 12 SET DATA READY FLAG Fig. 6E

STORE YELLOW SIGNAL IN OUTPUT REGISTER TRANSFER OUTPUT TO INPUT REGISTERSET DATA READY FLAG RESET WRITE FLAG STORE YE LLOW SIGNAL IN OUTPUTREGISTER TRANSFER OUTPUT TO INPUT REGISTER SET DATA READY FLAG OVER ORUNDER FLOW STORE GREEN SIGNAL IN OUTPUT REGISTER RESET WRITE FLAGINVENTORS Lawrence S. Michels George F IVImka Donald G-Kovar RobertHarper TORNEY PATENIEIJIIAR 6I975 3,719,927

SHEET lUUF 12 RESET WRITE FLAG RESET WRITE FLAG STORE YELLOW SIGNAL INOUTPUT REGISTER INVENTORS Lawrence S. Michele George F Mmko DonaldGKovgr Egg: Robert Harper ATTORNEY PATEr-HEDMAR ems 3,719,927

SHEET llUF 1 NEGATIVE MODE WAIT FOR WRITE CYCLE RESET WRHE "I686 FLAGRESET RECORD COUNTER Fig.6G

LOOK FOR TURN ON RECORD SYNC WRITE ENABLE INCREMENT WRITE THE RECORDCOUNTER PREAMBLE e94 \NVENTORS Y Lawrence S MicheIs George F lvhnko fe95 697 Donald uKovcn N Robert Harper WRITE ZEROS FOR DATA WRITE ACCOUNTRECORD NUMBER BY Z/ ATTORNEY PATENTEDIIIR 6 I975 SHEET 12 [IF 1 WRITE SI52 STATUS INDICATOR WRITE ZEROS FOR AMOUNT WRITE TEST AMOUNT WRITEAMOUNT WRITE PARITY BIT FiqEBH TURN OFF WRITE ENABLE I RESET WRITE FLAGINVENTORS Lawrence S Michels George F. Minko DOnOId G-Kovor RobertHarper ZYW ATTORNEY CREDIT CONTROL SYSTEM BACKGROUND OF THE INVENTION Inlarge retail stores, the problem of checking the identity of aprospective credit customer, the status of his account and his creditbalance is as old as retail stores themselves. Very early credit controlsystems customarily referred each credit sale to a credit man whosespecial duty was to keep track of credit customers so as to be able topass judgment upon the responsibility of each purchaser. Considerabledelays between the request for credit approval and approval of creditwere common as it was necessary to send a messenger to the credit manwith a charge slip to be verified and await the return of the messenger.

By the turn of the 20th century, many stores had installed pneumatictube systems to replace runners. Pneumatic tube systems were still notfast enough for the ever increasing pace of business.

With the advent of the telephone, stores were able to avoid thisannoying delay and secure immediate authorization for the credit SeeU.S. Pat. No. 939,245 to Jacob Oscar Greenwald which discloses a creditcontrol system employing telephones and electrical check punching orimprinting devices at various substations which are connected with acentral station where the credit man or the authority for extendingcredit is located with his records.

According to the Greenwald patent, when goods are ordered to be chargedon account, the clerk or attendant at the station places the sales slipin an authorization device and telephones to the credit man the name andaddress of the customer, the amount of the purchase, and likeinformation. The credit man looks through his card indexes or otherrecords to determine whether the customer is entitled to credit. If thecustomer is entitled to credit an authorization switch is pressed, andthe credit authorization unit stamps the sales slip. See, for example,the system disclosed in U.S. Pat. No. 975,533 to Charles F. Kettering.

The basic system disclosed in these early patents, circa 1910, is thesystem used today by many department stores. The only improvements havebeen that account numbers are used instead of names, and in some stores,the credit records have been computerized to permit real time videodisplay.

In the early l960s,a number of credit account verification systems weredeveloped. These systems employed memory storage units which held thenames or account numbers of all customers, and the statusof theiraccount, i.e., good or bad. These systems required large expenditures ofcapital to install, and many stores refused to make the investment.These systems are socalled positive" systems as they store the accountnumbers for every customer, and positively identify him. See U.S. Pat.No. 3,212,062 to R. N. Goldman et al.

An improved system was developed which stored only the names of badcustomers. By simply determining whether a match existed between aprospective credit customers account number and the account numberslisted on the bad list, approval or denial of credit could beaccomplished. See U.S. Pat. No. 3,344,258 to Lawrence S. Michels andassigned to the same assignee as the present invention, and U.S. Pat.

, No. 3,465,289 to Ronald L. Klein, which discloses a validity checkingsystem. These patents are directed to so-called negative systems becausethey typically store only bad accounts.

None of the prior art systems, however, provide for checking the creditbalance of a prospective credit customer. They merely provided a checkas to the validity of a credit account. It is for this reason that suchvalidity checking systems have not found wide acceptance in the field. I

It would be desirable, therefore, to have a credit control system whichwould be capable of checking the status, and current credit accountbalance for each' credit purchase without resorting to telephoning acredit man for each purchase and asking him to look up the relevantinformation; yet still provide the speed of computerized validitychecking systems.

SUMMARY In accordance with an example of a preferred embodiment of thepresent invention, selected customer account numbers, status, creditlimit and account balance are stored in a memory. Each account isassigned an individual credit limit. When the credit limit of theaccount is reached, a warning is indicated. The limit of the customermay be extended at the discretion of a credit man, based on accountinformation which is available to him at any time through the use of aspecial terminal at the credit office.

At the time of each transaction, the sales clerk queries the memory asto customer account number and amount of purchase. The verificationstatus is checked and the total accumulated amount (including thecurrent purchase) is compared with a test amount. If a customer exceedshis test amount limit at the time of the transaction or has a restrictedverification status, an indication is provided to the sales clerk, andthe credit office is alerted. At the credit office, a credit man makesdisposition based upon data obtained from the information stored in thememory or from past payment records or credit history. An authorizerunit allows the credit man access to this data and allows him to alterthe contents as to verification status and credit limit. Thus the creditlimit can be waived for a particular transaction or raised accordingly.

The system, therefore, permits almost instantaneous verification of eachpurchase for customers having valid accounts making purchases that donot cumulate over their assigned credit limit. If the customer exceedshis limit, instant authorization may be obtained for each purchase usingthe credit authorizer unit.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram of an exampleof a preferred embodiment of a credit control system according to thepresent invention;

FIG. 2 is a block diagram of a typical chain store installation of acredit control system according to the present invention;

FIG. 3 is a perspective view of a keyboard unit;

FIG. 4 is a perspective view of the control and display of an authroizerunit;

FIG. 5 is a flow chart of the credit control system shown in FIGS. 1 and2;

FIG. 5A is a flow chart of the credit control system of FIG. 5 operatingin the positive by exception mode; and

FIGS. 6A-6I-I taken together are a flow chart of a central processor forthe credit control system of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of theinvention utilizes the positive by exception mode of operation. Underthis mode of operation, only exceptional customers are placed on thememory file at the time of the initial file load. Exceptional customersmay be those with credit ratings both above and below the norm. Thememory file may also include accounts active during the previous month.When a transaction takes place by a customer not on the exception oractive list, he is assigned a set of norm parameters and placed on thememory file. Thus, the system is fully positive in the sense that everytransaction is recorded, but the file size does not have to be anylarger than that required to handle the exceptions plus the activeaccounts.

Referring to FIG. 1, the credit control system of the present inventionmay consist of four basic subsystem units, a keyboard group 10, a bufferunit 11, an authorizer unit 12 and central processor 13. Enquiry datamodem 14 and control data modem 15 may be included if the data enquiryportion (consisting of keyboard group 10, buffer unit 11 and authorizerunit 12) of the system communicates with the central processor overtelephone lines.

A functional description of the system will be given first, followed byan analysis of each subsystem unit and ananalysis of a flow chart of thecentral processor, which is the heart of the system.

FIG. 2 shows an example of a chain store installation of a creditcontrol system according to the present invention. Keyboard groupcomprises a plurality of keyboard units 101a, 101b, 101e, 10ln where nis the number of point-of-sale stations in use by the store. For a givennumber of keyboard units, a volume load factor determines the amount ofother subsystem equipment required to support the level of keyboardactivity. Typically, up to ten keyboard units 101 feed one buffer module1 10.

7 Each keyboard unit 101 enters the account number and amount ofpurchase into the credit control system. FIG. 3 shows a perspective viewof a typical keyboard unit. The function of the keyboard unit beginswhen the sales clerk presses a SEND button 102. If a white light appearsat 103, buffer unit 11 is clear of traffic. The clerk then proceeds toenter the account number and amount of purchase by pressing theappropriate data keys 104. These numbers are individually transmitted aselectrical impulses to a buffer module 110 in bufier unit 11 where theyare stored until the complete message is assembled.

The reply is displayed as one of seven possible answers available fromthe combination of three colored signal lights 105,106 and 107. Signallight 105- may be green, light 106 yellow (amber) and light 107 red. Theseven possible answers are made up of six predetermined customer statusindications plus an all three on system check indication.

The green, amber and red lights 105-107 are simul taneously displayed(all three on) during data entry as each key is pressed. This tests thelights and indicates that the buffer module has accepted that particulardigit. If lights'105-107 are simultaneously displayed as a replyfollowing a data entry, it indicates that a keying or communicationerror has occurred. and that the enquiry should be repeated.

From the time the white light appears at 103 on a particular keyboardunit, for example keyboard unit 101a, until the answer display lights105-.-l07 go out, all the other keyboard units connected to the samebuffer module a areinoperative; thus keyboard unit 101b cannot operateto interfere with keyboard unit 101a. This action is performed by buffermodule 1 10a which also contains automatic timers for shutting off anactive keyboard unit if an operator should start an enquiry and fail tocomplete it. If more than 4 seconds pass between the key depressions,buffer module 110a will disconnect from keyboard unit 101a and theoperator must start over. This feature prevents one keyboard unit frommonopolizing the buffer unit.

Buffer unit 11 comprises a plurality of buffer modules 1 10 and aplurality of communication adapter modules 111. Each buffer module 110can accommodate a number of keyboard units 101 as determined by thevolume. A pair of communication adapter modules 111 can accommodate upto 16 buffer modules. 7

Each buffer module 1 10 acts as a rate buffer between the'keyboard datainput rate and the output to the central processor 13. Thus the manyseconds of operator time spent pressing keys is kept out of the centralprocessor which completes an inquiry and answer in machine time. Toaccomplish this, usingprinciples well known in the art,'the bufferstores each digit until the complete message is assembled. Then, themessage is transmitted through communication adapter module 1 11 tocentral processor 13. When central processor 13 returns the answer viathe communication adapter module 11 1, the proper buffer modulel 10stores it for the appropriate keyboard unit 101.

Communication adapter modules 111 act as data collection points for upto 16 buffer modules 110 and provide timing and control for telephoneline transmission via modems 14 and 15. When an electronic ready signalis sent from a buffer module 110, communication adapter module 111 willlock on to the sending buffer module 110 if it is not in use by anotherbuffer module, serve it, and return an answer. When the response iscompleted, communication adapter module 11 1 scans the buffer modules110 for new signals.

Authorizer unit 12 enables the credit man to release or reject the salein progress at an outlying credit point. Authorizer units may be locatedat each branch store, or at a central location. Each authorizer 12allows the credit man to communicate with the data stored in datastorage unit 131 of central processor 13. It is to be understood, thatthere may be any number of authorizer units operating substantially inparallel for any given credit control installation according to thepresent invention. Every unit is identical.

Each authorizer unit 12 may consist of two units, a control and displayunit 121 (shown in FIG. 4) and an electronics unit 122. .As an optionalfeature, a printer 123 may be used to record all the transactionsperformed by the authorizer. An example of a printer which can be usedwith the present system is model EP 101 manufactured by Seiko Company.

Authorizer unit 12 is used to update, delete or add an individualaccount or to change the test amount or status condition of anindividual account. The new information is entered via authorizerkeyboard 1211, shown in FIG. 4, which generates the electrical impulsesnecessary to transmit the data to authorizer. electronics unit 122 wherethe data bits are stored until one complete message is received.

When the entire message is received by electronics unit 122, it istransmitted through communication adapter 111, similar to the manner inwhich data from keyboard unit 101 is transmitted via buffer module 110,to central processor 13. When the data arrives at the central processor,the memory files of data storage unit 131 will be altered accordingly.If printer 123 is used, both the authorizer transmission and theprocessor reply are recorded.

The authorizer unit typically is notified when a sales clerk making aninquiry via a keyboard unit 101 receives a reply that the customer has,for example, exceeded his credit limit, or is behind in his payments.

An operator or credit man in the credit office operates the authorizerto make a disposition based upon data obtained from data storage unit131 or from master file information such as credit records or paymenthistory. The authorizer allows access to the data in storage unit 131and the master file, and permits alteration of the contents of storageunit 131 as to verification status, a credit limit and accumulatedamount.

The operator of authorizer unit 12 may direct the sales clerk not tocomplete the transaction or alter the data in storage unit 131 so thetransaction will not be restricted, and then direct the sales clerkaccordingly. Alteration of data may be accomplished by changing theverification status, changing the test amount (credit limit), changingthe accumulated amount or releasing the transaction for one purchaseonly.

The authorizer permits the operator to perform a number of differentfunctions. When ENQUIRE button 1212 is depressed, the status and amountinformation associated with a particular account number is flashed onscreen 1213. Depressing UPDATE button 1214 allows the operator to entera new account number, status and amount data or to alter the statusamount data via keyboard 1211. DELETE button 1215 causes deletion of anexisting account record. RELEASE-l button allows the operator to clearcredit for a single transaction which, otherwise would be barred. Thisoperation must follow an ENQUIRY. DEBIT button 1217 is depressed whenthe operator transmits an amount he wishes added to the accumulatedtotal. CREDIT button 1218 is depressed when the operator transmits anamount he wishes subtracted from the accumulated total. CLEAR button1219 isused to clear any error made during data entry prior todepressing SEND button 1220 or to clear the system before any dataentry. SEND button 1220 is used to begin system processing after alldata has been properly assembled and entered into the authorizer unit.SKIP button 1221 allows the operator to by-pass one or two data fieldsin order to enter the data in a desired portion of the memory file, orto cause the accessory printer unit 123 to advance paper. Keyboard 1211enters the account data into the system by depressing desired numberedpush-buttons. See FIG. 4.

Central processor 13 may comprise a distributor unit 132, a plurality ofprocessor units 133, data storage units 131 and a tape-to-disk unit 134.A full description of the operation of central processor 13 followsbelow with reference to FIG. 6.

Distributor unit 132 functions as a traffic control" device to monitorand relay signals to and from the communication adapter modules 111 andprocessor units 133. The distributor is programmed to give priority toanswers over inquiries. If any processor unit 133 has an answer to anyinquiry, the distributor accepts the answer from the processor unit 133and transmits it back to the sending communication adapter module.

Distributor unit 132 consists of a distributor 1321 and an optionalcheck digit verification module 1322.

A distributor 1321 may poll up to 16 communication adapters. When acommunication adapter module 111 sends an inquiry, distributor 1321accepts the information, performs error checks, and transmits it to anavailable processor unit 133. If the message is error free, processorunit 133 starts its cycle. If a message error is detected, distributor1321 gives an abort indication to processor 133 and sends an errormessage to .the transmitting communication adapter. When thiscommunication is complete, distributor 1321 resumes polling thecommunication adapter modules for new inquiries.

Check digit verification module 1322 is an optional feature of thedistributor unit. When a message comes in from a communication adaptermodule 1 11, a check digit verification is made. If a check digit erroroccurs, the distributor will return an error message to the sendingcommunication adapter, and inform the signal processor to abort.

Each processor unit 133 consists of a processor module 1331, and twomemory signal processor modules comprising a read matrix 1332 and awrite matrix 1333. Processor module 1331 performs the logical decisionfunctions and the read and write matrices 1332 and 1333 provide theinterfacing and signal conditioning required for connection to thestorage unit 131.

When processor unit 133 receives an input message, it electronicallycompares the incoming data with account numbers and credit statusrecorded in data 'storage unit 131. When the account number, as-

sociated status, and dollar amount information are located, processorunit 133 determines whether or not there is a restricted status andwhether or not the amount of purchase plus the previous total exceedsthe credit limit of the customer.

If the status of the account is restricted, processor 133 returns therestricted status code as part of its answer and does not update theinformation in the storage unit. The clerk receives a signal indicationthat the transaction cannot be completed.

If the status of the account is non-restricted, the new amount of thepurchase is added to the accumulated amount and the sum compared againstthe test amount (credit limit). If the new total is acceptable, it isrecorded in storage unit 131. The data now stored in storage unit 131 isthe account number, status, test amount and new accumulated amount. Agreen answer will go back to a keyboard unit 101 indicating the sale isacceptable and the processor has accepted it by updating the datastorage unit.

If the status is non-restricted, but the amount of the new saleplus theprevious total will exceed the test amount, a yellow status code isreturned to keyboard unit 101 and the transaction is not accepted by theprocessor. The new amount will not be stored because of the yellowsignal. The yellow signal informs the clerk at the keyboard not toaccept the sale until some action is taken by the credit office. Anauthorizer unit 12 is activated by the yellow signal, and a clerkperforms the necessary operations described in the section on authorizerunit 12.

If the input message calls for update or delete, the contents of datastorage unit 131 will be altered. In the case of an update, processormodule 1331 will search the data storage unit 131 using read matrix1333, find the location of the account number, and enter the new accountnumber via write matrix 1332. This new information can change any partof the status or amount fields. If the account number cannot be located,processor module 1331 will find an empty location in the file and enterthe new data. If the input message calls for delete, processor unit 1331searches the file via a read matrix 1333, locates the account number,and deletes it from data storage unit 131.

If the status digit associated with the input account number indicates aclear for one transaction, processor unit 133 adds the new amount of theprevious total, enters the new total on the file 131 via write matrix1332, and returns a green answer independent of whether or not the testamount is exceeded or if the original status digit was restricted.Processor module 1331 recognizes this as RELEASE l by means of a flag(electronic signal) on the status digit. This flag was originally placedin data storage unit 131 in the manner of an update asdescribed above.Processor module 1331 removes this flag when the inquiry for thisaccount is cleared for one transaction.

The capability of subtracting a desired amount from the accumulatedamountin data storage unit 131 is another mode of operation. Thesubtract mode command is controlled exclusively by authorizer unit 12,-entries from keyboard units 101 are limited only to the add mode.Processor module 1331 enters the subtract mode upon receiving an ENQUIRYcontrol character and a predetermined S1 digit. (This will be explainedin detail later.) Subtraction v is then carried out independent of thestatus of the digits stored in data storage unit 131, and all limitconditions are ignored. If a negative amount results, processor module1331 causes write matrix 1332 to write zeros into data storage unit 131for the amount field.

Data storage unit 131 provides the central file storage and interfaceswith processor units 133. It is capable of storing new or updatedinformation in a non-destructive manner and will read out all storedin-- formation. Storage unit 131 may provide'a magnetic disk as thestorage media. The capacity of the disk is determined by account volumenumber. For example, five storage unitswill, store 500,000 accountsincluding a digit account number, 2 digit status and 5 digit amount ofeach account.

Provision is made for updating a large number of accounts both forinitial file load and for periodic refreshing of data. This may be doneat the beginning of each month to update the data storage unit 131 tocover errors made in entering transactions, transactions not authorized,etc. A tape-to-disk unit 134 is used for this purpose. A prerecordedmagnetic tape 1341 is utilized for data transmission through a bufferstorage device 1342 to record new information in data storage unit 131.

A large number of accounts are updated as follows: A magnetic tape isprepared with the new information by a computer and is installed onmagnetic tape transport 1341. Transport 1341 sends the new informationto buffer and control electronics 1342. The buffer 1342 accepts andstores one block of account numbers at a time and determines, accordingto a code on the tape, on which track in data storage unit 131 the newinformation is to be recorded. The block of numbers is transmitted tostorage unit 131 and after verifying the integrity of the recording,accepts the next block of numbers from the tape. This process continuesuntil all the data on the magnetic tape has been recorded in datastorage unit 131.

It is within the scope of the invention to use a cardto-disk unitinstead of a tape-to-disk unit. For such case, a card reader would feedthe buffer and control electronics.

The detailed operation of central processor 13 will be explained withreference to FIGS. 5 and 6. FIGS. 5 and 6 are logic flow charts forcentral processor 13. FIG. 5 is the equivalent of a block diagram flowchart, and FIGS.- 6A-6H which comprise FIG. 6 are the equivalent of acircuit type diagram flow chart in that it fully details the operationof central processor 13. Conventional flow chart notation is used inboth FIGS. 5 and 6, with rectangular blocks'indicating processes oroperations to be performed. Diamond blocks represent a comparison to bemade, a particular branch root being taken from the diamond box when themathematical relationship associated with that root represents in factthe comparison of those quantities listed within the block; or aparticular exit root is taken from the diamond block when the conditionassociated with that root represents in fact the condition determined bythe required' operation.

FIG. 5 is a flow chart of the credit control system and shows thesequence of events for the three modes of operation possible using thecentral processor disclosed in the present invention. The three modes ofoperation are negative, full positive and positive by exception. Apreferred embodiment of the invention is the positive by exception modeof operation. In the negative mode of operation only the bad orquestionable accounts are stored on the file in the memory. Hence, whenthe memory is scanned, if the account number is not found this indicatesthe status to be good, thus causing a green light to be lit. If theaccount number is on the file, then the status of the account number isdetermined and the appropriate status response is sent back to thekeyboard to light either a yellow or red light. For a full understandingof a mega tive system, see U.S. Pat. No. 3,344,258 to Lawrence S.Michels and assigned to the same assignee as the present invention.

In the full positive mode of operation all valid and active accountnumbers are stored on the file. A preliminary check is made to insurethat the account number checked is in fact on the file. If it is not,either a yellow or red response is called for. If the account number ison the file, the status is checked and if good, the accumulated amountplus the purchase amount is compared with the test amount. If theaccumulated amount plus purchase amount is less than the test amount, agreen status response is sent back and the new purchase amount data isentered on the memory.

In the positive by exception" mode of operation, only those accountnumbers which are active accounts or very good or' very bad credit risksare stored on the file. Unlike the full positive mode of operation,credit customers having a good credit rating may not be stored on thelist. If the account number is on the file, the procedure is the same asfor the full positive system. If the account number is not on the file,then determination is made whether the purchase amount is greater thanthe test amount which is set for account numbers not stored in thememory file. If the purchase amount is less than the test amount, thepurchase amount is written into the memory and stored therein. A greenstatus response is then sent back to the appropriate keyboard.

A full explanation of the block logic diagram of FIG. follows. The cycleis initiated by a start operation 501 when the account number and amountof purchase are entered, and thereafter passes through a sequence ofoperations represented by blocks 502 through 516. The final operation isterminate 517. Three major loops are involved in this cycle; they arethe negative loop, the full positive loop, and the positive by exceptionloop. The following description of the separate component blocks of theblock diagram also indicates the interrelationships of these components.

Block 502 Initiation of the start operation causes block 502 to checkthe validity of the account number. This means that a check digitverification operation is performed. If the account number is not validthen a status response is sent back to the keyboard causing for example,the red, yellow and green lights to appear.

Block 503 For negative operation, the memory file is searched todetermine if the account number is on file. If the account number is noton file, a green status response is sent back to the keyboard group. Ifthe account number 'is on file then the status response on file is sentback to the keyboard group.

Block 504 This block sends the status response appearing on file backto'the keyboard group. At this point the cycle terminates at block 517.

Block 505 This block is the start of full positive operation. The memoryfile is searched to determine if the account number is stored therein.If the account number is not stored therein it must not be a goodaccount, therefore either a yellow or red light is lit at theoriginating keyboard. The choice of red or yellow is determined bycustomer preference.

Blocks 506 and 507 Block 506 determines whether the status of theaccount number on file is restrictedor not. If the status is restricted,then block 507 sends the status response on file back to the appropriatekeyboard.

Blocks 508 510 If the status is not restricted as determined by block506, then a comparison is made in block 508 to see if the credit balanceis positive or negative. This is done by determining whether theacamount. The test amount is determined by customer preference. If theaccumulated amount plus amount of the current purchase is greater thanthe test amount, then a yellow response is sent back to the keyboardgroup. Note that at this point the authorizer unit 121 comes into use asexplained above. If the accumulated amount plus amount of presentpurchase is less than the test amount, block 509 adds the purchaseamount to the accumulated amount in the memory file and block 510 sendsa green status response back to the keyboard group. At this point thecycle terminates at block 517.

Block 51 1 The logic diagram of positive by exception mode of operationbegins in block 511 where the memory file is searched to determine ifthe account number is on file.

Blocks 512 514 If the account number is not on file as determined byblock 511, then block 512 compares the purchase amount with a testamount. The test amount of block 512 may be the same as, or differentfrom, the test amount of block 508. If the amount of the presentpurchase is greater than the test amount, a yellow light is sent back tothe keyboard group and authorizer 121 is put into use. If the amount ofthe present purchase is less than the test amount, block 513 writes theaccount number, status, test amount'and purchase amount into the memoryfile. Block 514 sends a green status response back to the keyboardgroup. The cycle terminates at block 517.

Block 515 If the account number is on file, as determined in block 511,then the determination is made as to whether the status of the accountlisted is restricted. If the status is not restricted then theoperations of blocks 508 through 510 are performed and the cycleterminates at 517.

Block 516 If the status is restricted, then block 516 sends the statusresponse on file back to the keyboard. At this point the cycleterminates at block 517.

For clarity and convenience the positive by exception mode of operationis reproduced in FIG. 5A.

As will be seen later, the authorizer unit may override yes output fromblocks 508 and 512. This means that in the event the accumulated amountplus the.

amount of the current purchase is greater than the test amount, theauthorizer unit can manually enter a new test amount for a singlepurchase only and change the tions to permit operation in positive andnegative modes will be explained where appropriate. In the explanationof the processor flow chart of FIG. 6, reference is made to FIG. 2 whereappropriate.

The plurality of letters within circles appearing throughout the sheetsof FIG. 6 indicate the points of connection between the sheets.

Block 600 The cycle of central processor 13 is initiated by start block600.

Block 601 Block 601 polls the various processor units 133 to determinewhich of the plurality of processors is available to accept data. Theprocessors are polled in a predetermined order until a free processor isavailable.

Blocks 602 608 Block 602 determines if the data ready flag is set. Ifthe data ready" flag is set, block 603 sends information stored in anoutput register" back to the originating keyboard thus effecting anoutput of data. After the information is sent back to the keyboard,block 604 resets the data ready flag and block 606 initializes the cycle(or program) when block 605 determines that the write flag has beenreset. When the write flag is set, storage unit 131 is in the writemode, and when the write flag is reset, storage unit 131 is in the readmode. Block 607 sets the processor available flag. When the processoravailable flag is set, it indicates that a particular processor isavailable for an inquiry. When the processor available flag is reset, itindicates the processor is busy. If the data ready flag is reset, block608 determines whether the processor available flag is set. If theprocessor available" flag is reset, and a processor is not available,the program returns to start.

Blocks 609 612 If the processor available flag is set, indicating aprocessor is available for use, distributor input block 609 determineswhether data is input data from a keyboard or output answer. If the datais output data, block 610 loads the data from the processor, block 611holds the data for release, and block 612 is the release indicating thatthe processor should abort because the data is output data.

Blocks 613 615 If the distributor is set so the processor is receivingdata from the keyboards, or any other terminal, block 613 stores theaddress of the processor to which the information is sent in a zerocounter, and block 614 stores the address of the communication-adapter(and thus keyboard) from which the data came in an output register."Block 615 loads the input data from the keyboard to the processor.

Block 616 Block 616 stores the control character indicative of the typeof operation which the device is performing. The types of inquirytypically are: update the file, delete a name from the file, or a normalcredit check. The first two mentioned operations are usually initiatedfrom, an authorizer unit 12, or from the tapeto-disk unit 134.

Block 617 Each storage disk may contain a plurality of tracks. Althoughit is not necessary for the operation of the invention, it is sometimesdesirable to havemore than one track to speed up'the scanning process,and therefore the response time for an operation. Block 617 stores theaddress of the trackor the portion of the'disk where the account numberinquired about is located.

Block 618 This block stores data as to the nature of the inquiry withrespect to whether it is a debit inquiry (add to-credit balance) or acredit inquiry (subtract from credit balance).

Block 619 and 620 Block 619 determines if there is a check digit erroror input error or some other error in the information received from thekeyboard. If there is an error the system resets. If there is no erroran addi-- tional determination is made in block 620 to determine if.there is a valid control characterylf there is not a valid controlcharacter, the system resets and goes back to the start of the cycle.

Blocks 621 623 If there is a valid control character, block621 resetsthe processor available flag to indicate that the particular processoris busy and will not receive more inquiries. The storage disks locatedwithin central processor units 13 have a predetermined read cycle duringwhich it is possible to scan all the information stored on the storagedisk. Block 622 waits for the start of the read cycle to insure thatevery account number may be scanned. At the start of the read cycle,block 623 resets a record counter. The record counter" accounts for thenumber of individual records or account numbers on the disk, so that anaddress location for the account number can be determined. The recordcounter is not to be confused with systems that store a particularaddress for each account number and when queried locates the accountnumber by the particular address. The record counter of the presentinvention is reset at the beginning of each read cycle.

Blocks 624 629 The loops starting with blocks 624 and 630 occursimultaneously. Block 624 instructs the processor module 1331 to lookfor an open location on the storage disk or memory file. In the eventthe account number inquired about is not on the storage disk or memoryfile an open location and its address are determined. The search for anopen location occurs as follows: as the storage disk or memory isscanned, as each address location is reached block 625 determineswhether or not that location is filled. If the location is filled, block632 increments the record counter. When an open location is reached,block 626 resets the track full flag. Thus the number stored in therecord counter" at the time the track full flag is reset is the addressof the open location. Block 627 determines if the account numberinquired aboutis'equal to an account number in the memory. That is, ifthe account number inquired about is stored in the memory. If theaccount number is found in the memory, the address s of the number ofinterest determined by the record counter is stored. If the accountnumber. is not on the memory file, Block 628 stores the address locationof the blank location. Hence, at termination block 629, either theaddress of the blank location or the address of the number of interestis stored.

Blocks 630- 634 Block 630 commands block 631 v to search the memory filefor the account number of interest. The file is searched record byrecord until the account number of interest is found or until the end ofthe read cycle is reached. The searching is done by comparing eachnumber on the file to the account number inquired about. If no match isfound, block 632 increments record counter, and upon a match between theaccount number of interest and the number stored in the record file,block 634 stores status symbols in the output register. Block 633determines when the end of the read cycle is reached. The loop from 630to 633 is traversed once for each account number on the file. Thesymbols S1 and S2 indicate the status of the account number stored.

Blocks 635 640 Blocks 635 acts in response to the flag stored by block618. If the transaction is a debit transaction debit block 637 adds theinput amount to the stored amount. If the transaction is a credittransaction, block 636 subtracts the input amount-from the storedamount. The results of the activities of blocks 636 and 637 are storedin an output register by block 638. Block 639 causes the test amount,which is a predetermined credit limit set by the store, to be stored inthe output register. Block 640 is an error detector that checks parityof the record on file. If there is a parity error, the account number isconsidered not equal, and the record counter is incremented by block632.

Block 641 This block resets the track full" flag when the desiredaccount number is located on file. Block 641 has a similar function toblock 626.

Blocks 642 644 Block 642 stores the number contained in the recordcounter in. the address register. Thus the address location of thedesired account number is stored in the address register. Block 643 setsa write flag and block 644 determines whether the type of inquiry is acredit check in which case the yes" path from block 644 is followed, oran update or delete in which case the "no path from block 644 isfollowed. Block 644 makes the determination based on the controlcharacter stored by block 616.

Blocks 645 646 These blocks perform essentially the same functions asblocks 643 and 644 respectively except that the desired account numberwas not found on tile.

Block 647 651 Block 647 determines if a particular track on the storagememory is full. If the track is full, block 648 resets the write flag,and block 649 stores an appropriate status symbol, i.e. yellow lightsignal, in the output register. Block 603 outputs the data back to thekeyboard group on command, and block 606 initializes the program foranother operation. If the track is not full, block 650 determineswhether the write flag is on. If the write flag is not on block 651determines whether the data ready flag is set. If the data ready flag isset, the system, in effect, idles until the data ready flag is reset.When the data ready flag is reset, the output returns to the beginningof the cycle (or program). The normal procedure is, however, that thewrite flag is on, whereupon the system prepares to write the informationonto the storage memory as will be explained later.

Blocks 652 e 654 If the desired account number is not on file, block 652stores the dollar amount of the sale, entered via the keyboard group inthe output register. Block 653 stores the test amount in the outputregister. Recall that the test amount is the standard open to buy orCredit limit which is predetermined. Block 654 determines whether thedollar amount of the sale is over the test amount or credit limit.

Blocks 655 658 If the amount .of the sale is not over the test amount,block 655-stores a valid credit or green light signal in the outputregister, thus paving the way for a green light at the keyboard group.Block 656 transfers the output data from the output register to the"input register. Data stored in the input register" ultimately iswritten onto the file. Block 657 sets the data ready" flag to signal thedistributor that the data is ready to return to the keyboard. Block 658determines whether the transaction is a "debit" or credit" transactionin accordance with the "add/subtract flag stored by block 618. If block658 determines that the transaction is a debit transaction, theinformation is passed along to be written onto the file.

Block 659 If the transaction is a credit" transaction, indicating that acustomer is not on file is perhaps paying a bill, block 659 resets thewrite flag to prevent an entry onto the memory file.

Blocks 660 662 lf block 654 determines that an over limit exists,meaning that the dollar amount of the sale exceeds the credit limit fora particular customer, block 660 stores a yellow indicator in the outputregister, block 661 transfers the data in the output register to theinput register. Block 662 sets the data ready flag and as before block659 prevents entry onto the memory file.

Blocks 663 665 These blocks are used only when the system is programmedto operate in a full positive mode. Block 663 determines if the systemis programmed to operate in a positive mode. If the system is notoperating in a full positive mode, block 650 determines if the writeflag is on as explained above. If the system is operating in a fullpositive mode, block 664 stores either a yellow or red light signal inthe "output register, and block 665 resets the write flag" to preventwriting onto the memory file.

Blocks 666 and 667 Authorizer unit 12 has the ability to release, forone transaction only, a purchase which, when totaled with pastpurchases, exceeds the credit limit of the customer. Block 666determines if the authorizer has released for one transaction. If so,then block 667 resets the 8, flag thus bypassing restricted status block669 and overlimit check 674 to permit a release. A green light is sentback to the keyboard for the present transaction only.

Block 668 This block makes a decision in response to the add or subtractflag stored by block 618. If the subtract flag is stored, it indicatesthe customer is probably paying a bill, hence the restricted statusblock 669 and overlimit check 674 portion of the cycle is skipped.

Blocks 669 and 670 Block 669 determines if the status stored in theoutput register is restricted (not green). If so, block 670 sets thedata ready flag which signals a distributor unit that data (not greensignal indication) is ready to return to the keyboard.

Blocks 671 673 Overflow block 671 determines whether the accumulateddollar amount inquired about is greater than the system capacity. if theaccumulated dollar amount inquired about is greater than the systemcapacity, block 672 stores a yellow light status indicator in the outputregister. Block 673 then resets the write flag" to prevent writing ontothe memory file. If the accumulated amount is within the capacity of thesystem, the status digits read from thefile remain in the outputregister, and block 673 resets the write flag. Block 603 starts theoutput of data back to the keyboard as explained above. Thus the statussymbols stored in the output register by blocks 649, 655, 660,.

664, 672, 675 and 683 are transferred ultimately to the keyboard wherean appropriate light signal is displayed.

Block 674 Block 674 determines whether the accumulated amount exceedsthe test amount. This operation is equivalent to that shown in block 508of FIG. 5.

Blocks 675 678 If the accumulated amount exceeds the test amount, block675 stores a yellow light status indicator in the output register. Block676 transfers the yellow light status indicator singal stored in theoutput register to the input register, block 677 sets the data readyflag and block 678 resets the write flag." The data stored in the outputregister is ultimately transferred to the keyboard where an appropriatelight signal is displayed.

1. A credit control system comprising: a memory for storing customeraccount identification symbols, credit status symbols, credit limitsymbols and accumulated balance symbols; first means for loading intothe memory said customer account identification symbols, credit statussymbols, credit limit symbols and accumulated balance symbols;coincidence means for comparing a generated customer accountidentification symbol to be checked with thE customer accountidentification symbols stored in said memory, said coincidence meansproducing signals indicating the presence or absence in the memory ofsaid generated customer account identification symbol; second means,responsive to the absence of said customer account identification symbolin said memory, for comparing a purchase amount symbol associated withsaid generated symbol with a preselected credit limit to determinewhether the purchase amount symbol associated with said generated symbolexceeds the preselected credit limit; third means, responsive to adetermination that said purchase amount symbol associated with saidgenerated symbol does not exceed said preselected limit, for loadingsaid memory with said generated customer identification symbol, anappropriate status symbol and said purchase amount symbol associatedwith said generated symbol; fourth means, responsive to the presence ofsaid generated customer account identification symbol in said memory,for determining whether the status of the generated symbol isrestricted; fifth means, responsive to a proper status determination bysaid fourth means, for determining whether the sum of the accumulatedbalance associated with said generated symbol, and the purchase amountexceeds the credit limit for said generated symbol; and sixth means,responsive to a proper determination by said fifth means, for loadingsaid memory with the sum of the accumulated balance and current purchaseamount for said generated symbol customer account.
 1. A credit controlsystem comprising: a memory for storing customer account identificationsymbols, credit status symbols, credit limit symbols and accumulatedbalance symbols; first means for loading into the memory said customeraccount identification symbols, credit status symbols, credit limitsymbols and accumulated balance symbols; coincidence means for comparinga generated customer account identification symbol to be checked withthE customer account identification symbols stored in said memory, saidcoincidence means producing signals indicating the presence or absencein the memory of said generated customer account identification symbol;second means, responsive to the absence of said customer accountidentification symbol in said memory, for comparing a purchase amountsymbol associated with said generated symbol with a preselected creditlimit to determine whether the purchase amount symbol associated withsaid generated symbol exceeds the preselected credit limit; third means,responsive to a determination that said purchase amount symbolassociated with said generated symbol does not exceed said preselectedlimit, for loading said memory with said generated customeridentification symbol, an appropriate status symbol and said purchaseamount symbol associated with said generated symbol; fourth means,responsive to the presence of said generated customer accountidentification symbol in said memory, for determining whether the statusof the generated symbol is restricted; fifth means, responsive to aproper status determination by said fourth means, for determiningwhether the sum of the accumulated balance associated with saidgenerated symbol, and the purchase amount exceeds the credit limit forsaid generated symbol; and sixth means, responsive to a properdetermination by said fifth means, for loading said memory with the sumof the accumulated balance and current purchase amount for saidgenerated symbol customer account.
 2. A credit control system as claimedin claim 1 and further including: means for performing check digitverification on the customer account identification symbol.
 3. A creditcontrol system as claimed in claim 1 wherein said memory is cyclicallyscanned by said coincidence means.
 4. A credit control system as claimedin claim 1 wherein said coincidence means for comparing the generatedcustomer account identification symbol with the customer accountidentification symbols stored in said memory comprise: means forcyclically scanning each customer account identification symbol storedin said memory; means for determining the start of a read cycle; aresettable record counter capable of incrementing in response to apulse; means for resetting said record counter at the start of a readcycle; means for comparing each customer account identification symbolstored in said memory with the generated customer account identificationsymbol; means for incrementing said record counter in response to apulse output from said comparator indicating each read symbol stored insaid memory is not the same as the generated symbol; an addressregister; and means for storing the count in said record counter in saidaddress register in response to an output from said comparatorindicating the read symbol stored in said memory is the same as thegenerated symbol.
 5. A credit control system as claimed in claim 4 andfurther including means for finding a blank location in said memorycomprising: means for looking for an all zero record; means forindicating the end of a read cycle; and means for storing the count insaid record counter in said address register in response to said meansfor looking for an all zero record; so that the number stored in saidaddress register represents the address of an available blank space insaid memory.
 6. In an automatic machine implemented method of checkingcredit which includes the steps of storing in an automatic machinecustomer account identification symbols, and associated credit statussymbols, credit limit symbols and accumulated balance symbols,generating a customer account identification symbol to be checked and apresent purchase amount symbol associated therewith, and determiningwhether the customer account identification symbol to be checked isstored in the machine, the improvement comprising the steps of:determining whether the present purchase amount is greater or less thana preselected credit limit if the customer account identification symbolto be checked is not stored in the machine; sending an appropriateinvalid credit status response if the present purchase amount is greaterthan the preselected credit limit; and storing in the automatic machinethe customer account identification symbol being checked, an associatedcredit status symbol, the preselected credit limit symbol and thepresent purchase amount, if the present purchase amount is less than thepreselected credit limit, and sending an appropriate valid credit statusresponse.
 7. An automatic machine implemented method of checking creditas claimed in claim 6 and further including the steps of: determiningwhether the associated credit status symbol indicates a restrictedaccount, if the customer account identification symbol to be checked isstored in the machine; sending an appropriate invalid credit statusresponse if the associated credit status symbol indicates a restrictedaccount; determining whether the present purchase amount added to theaccumulated balance is greater or less than the associated credit limitif the associated credit status symbol indicates a not restrictedaccount; and sending an appropriate invalid credit status response ifthe present purchase amount added to the accumulated balance is greaterthan the associated credit limit.
 8. An automatic machine implementedmethod of checking credit as claimed in claim 7 and further includingthe steps of: increasing the accumulated balance by the present purchaseamount; and sending an appropriate valid credit status response if thepresent purchase amount added to the accumulated balance is less thanthe associated credit limit.
 9. An automatic machine implemented methodof checking credit as claimed in claim 16 and further including thesteps of: increasing the accumulated balance by the present purchaseamount and sending an appropriate valid credit status response if thepresent purchase amount added to the accumulated balance is less thanthe associated credit limit; determining whether the present purchaseamount is greater or less than a preselected credit limit if thecustomer account identification symbol to be checked is not stored inthe machine; sending an appropriate invalid credit status response ifthe present purchase amount is greater than the preselected creditlimit; and storing in the automatic machine the customer accountidentification symbol being checked, an associated credit status symbol,the preselected credit limit symbol and the present purchase amount, ifthe present purchase amount is less than the preselected credit limit,and sending an appropriate valid credit status response.
 10. Anautomatic machine implemented method of checking credit as claimed inclaim 16 and further including the step of: performing check digitverification on the customer account identification symbol.